Steam supply system for superposed turine and process chamber, such as coal gasification

Abstract

A steam supply system is provided for use in conjunction with both a superposed turbine driven by a steam boiler and a process chamber. The steam boiler operates at a pressure above that needed for consumption in the process chamber and uses highly purified water. The process chamber can use steam which has been generated from relatively low purity water and may be any steam consuming process, such as in one embodiment coal gasification, not requiring that the water be returned for re-use as steam. Energy remaining in the high purity steam after it leaves the superposed turbine is used in a condensing reboiler to heat the water into steam for the process chamber. The two fluids are kept essentially isolated from contact with each other in the condensing reboiler, and the high purity water is pumped back to the high pressure boiler in a closed loop system. The use of high purity water to produce high pressure steam provides protection to the superposed turbine from fouling and damage, thereby extending both its operating range and useful life.

What is claimed is: 
     
       1. A steam supply system for a process chamber consuming superheated steam at a pressure of about 600 psi or below which is driven by a boiler operating at a pressure of about 2000 psi, a pressure range above that needed by said process chamber for also driving a superposed turbine, comprising: (a) a high pressure boiler feed pump for supplying highly purified water to said boiler;   (b) a condensing reboiler connected to receive steam from said superposed turbine in a high pressure side;   (c) said condensing reboiler also having a low pressure side, essentially isolated from fluid contact with said high pressure side, for receiving water for use in the lower operating pressure steam processes;   (d) said condensing reboiler further comprising integral superheating means for heating the wster received in said low pressure side into superheated low pressure steam with the steam received in the high pressure side;   (e) means for conveying fluid from said high pressure side of said condensing reboiler to said boiler feed pump; and   (f) means for conveying the low pressure superheated steam from said condensing reboiler to said process chamber.   
     
     
       2. The apparatus of claim 1, wherein said process chamber comprises means for gasification of carbonaceous fuel. 
     
     
       3. The apparatus of claim 1, further including: means for at least partially purifying the water to be received in said low pressure side of said condensing reboiler.   
     
     
       4. The apparatus of claim 3, wherein said purifying means includes: water softening means.   
     
     
       5. The apparatus of claim 3, wherein said purifying means includes: water demineralizer means.   
     
     
       6. The apparatus of claim 1, further including: pump means for supplying water to said low pressure side of said condensing reboiler.   
     
     
       7. The apparatus of claim 1, wherein: said feed pump, said boiler, said turbine and said high pressure side of said condensing reboiler are connected in a closed loop fluid flow path.   
     
     
       8. A process of supplying superheated steam for a process chamber consuming steam at a pressure of about 600 psi or below which is driven by a boiler operating at a pressure range above that needed by the process chamber for also driving a superposed turbine with steam at a pressure of 2000 psi or above, comprising the steps of: (a) supplying highly purified water to the boiler;   (b) receiving steam from the superposed turbine in a high pressure side of a condensing reboiler;   (c) receiving water in a low pressure side of the condensing reboiler having an integral superheater in fluid isolation from the high pressure side;   (d) heating the water in the low pressure side, with the steam received from the superposed turbine, into low pressure superheated steam;   (e) conveying fluid from the high pressure side of the condensing reboiler for supply to the boiler; and   (f) conveying low pressure superheated steam to the process chamber for use therein.   
     
     
       9. The method of claim 8, wherein: the steam consuming process is gasification of carbonaceous fuel; and   the useful work performed by the turbine is power generation.   
     
     
       10. The method of claim 9, further comprising the step of: demineralizing the water before passing the water to the low pressure side of the condensing reboiler.